Among the elderly, anemia occurs with increasing frequency with each advancing decade. Unlike when anemia occurs in younger adults, the cause of anemia in the elderly is oftentimes not readily apparent or attributable to a single cause. However, this commonly observed form of anemia in the elderly (termed Unexplained Anemia or UA) can generally be dissected to its root causes, which include renal insufficiency, inflammation, testosterone deficiency and stem cell proliferative decline. Myelodysplasia (MDS) occurs commonly in this age group but can and should, for both diagnostic and therapeutic considerations, be distinguished from UA.[unreadable] [unreadable] This research involves a comprehensive assessment of the mechanisms involved in the development of anemia in unselected patients and the functional consequences of anemia with regard to physical performance and quality of life. From this analysis strategies will be developed to assess whether correction of anemia will result in improvement in these (or other) selected parameters.